diff --git a/lib/services/api_client.dart b/lib/services/api_client.dart
index 5a1eec8..6e81662 100644
--- a/lib/services/api_client.dart
+++ b/lib/services/api_client.dart
@@ -3,7 +3,9 @@ import 'package:dio/dio.dart';
 /// HTTP-клиент для одного сервера Ignis.
 /// Покрывает все эндпоинты из openapi.json.
 class IgnisApi {
-  final Dio _dio = Dio();
+  IgnisApi({Dio? dio}) : _dio = dio ?? Dio();
+
+  final Dio _dio;
   Dio get dioInstance => _dio;
 
   static String normalizeBaseUrl(String baseUrl) {
@@ -70,11 +72,11 @@ class IgnisApi {
 
   /// Управление группой: state, brightness, temp, scene, r/g/b
   Future<Response> controlGroup(String id, Map<String, dynamic> params) =>
-      _dio.post('/control/group/$id', queryParameters: params);
+      _dio.post('/control/group/$id', data: params);
 
   /// Управление одной лампой
   Future<Response> controlDevice(String id, Map<String, dynamic> params) =>
-      _dio.post('/control/device/$id', queryParameters: params);
+      _dio.post('/control/device/$id', data: params);
 
   /// Мигнуть лампой (для идентификации)
   Future<Response> blinkDevice(String id) =>
@@ -92,11 +94,11 @@ class IgnisApi {
 
   /// Одноразовое расписание (таймер)
   Future<Response> scheduleOnce(Map<String, dynamic> params) =>
-      _dio.post('/schedules/once', queryParameters: params);
+      _dio.post('/schedules/once', data: params);
 
   /// Cron-расписание (повторяющееся)
   Future<Response> scheduleCron(Map<String, dynamic> params) =>
-      _dio.post('/schedules/cron', queryParameters: params);
+      _dio.post('/schedules/cron', data: params);
 
   /// Все активные задачи расписания
   Future<Response> getTasks() => _dio.get('/schedules/tasks');
diff --git a/test/api_client_test.dart b/test/api_client_test.dart
new file mode 100644
index 0000000..fde5c08
--- /dev/null
+++ b/test/api_client_test.dart
@@ -0,0 +1,86 @@
+import 'dart:typed_data';
+
+import 'package:dio/dio.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:ignis_app/services/api_client.dart';
+
+class RecordingAdapter implements HttpClientAdapter {
+  RequestOptions? lastRequest;
+
+  @override
+  Future<ResponseBody> fetch(
+    RequestOptions options,
+    Stream<Uint8List>? requestStream,
+    Future<void>? cancelFuture,
+  ) async {
+    lastRequest = options;
+    return ResponseBody.fromString(
+      '{}',
+      200,
+      headers: {
+        Headers.contentTypeHeader: ['application/json'],
+      },
+    );
+  }
+
+  @override
+  void close({bool force = false}) {}
+}
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+
+  test('controlGroup sends command payload in request body', () async {
+    final adapter = RecordingAdapter();
+    final dio = Dio()..httpClientAdapter = adapter;
+    final api = IgnisApi(dio: dio)..init('http://localhost:8000', 'secret');
+
+    await api.controlGroup('kitchen', {'state': true, 'brightness': 42});
+
+    expect(adapter.lastRequest, isNotNull);
+    expect(adapter.lastRequest?.path, '/control/group/kitchen');
+    expect(adapter.lastRequest?.queryParameters, isEmpty);
+    expect(adapter.lastRequest?.data, {'state': true, 'brightness': 42});
+  });
+
+  test('scheduleOnce sends schedule payload in request body', () async {
+    final adapter = RecordingAdapter();
+    final dio = Dio()..httpClientAdapter = adapter;
+    final api = IgnisApi(dio: dio)..init('http://localhost:8000', 'secret');
+
+    await api.scheduleOnce({
+      'target_id': 'hall',
+      'hours_from_now': 4,
+      'state': false,
+      'is_group': true,
+    });
+
+    expect(adapter.lastRequest, isNotNull);
+    expect(adapter.lastRequest?.path, '/schedules/once');
+    expect(adapter.lastRequest?.queryParameters, isEmpty);
+    expect(adapter.lastRequest?.data, {
+      'target_id': 'hall',
+      'hours_from_now': 4,
+      'state': false,
+      'is_group': true,
+    });
+  });
+
+  test(
+    'createApiKey keeps query-based contract until backend is changed',
+    () async {
+      final adapter = RecordingAdapter();
+      final dio = Dio()..httpClientAdapter = adapter;
+      final api = IgnisApi(dio: dio)..init('http://localhost:8000', 'secret');
+
+      await api.createApiKey('Guest', isAdmin: true);
+
+      expect(adapter.lastRequest, isNotNull);
+      expect(adapter.lastRequest?.path, '/api-keys');
+      expect(adapter.lastRequest?.queryParameters, {
+        'name': 'Guest',
+        'is_admin': true,
+      });
+    },
+  );
+}